1. Technical Field:
This invention relates to a system and method for finding and tracking the location of a subject's eyes.
2. Background Art:
Eye finding and tracking devices are employed for many purposes. For example, such devices are often used in vehicle operator drowsiness and intoxication detection systems. When a person is responsible for operating a vehicle, such as an automobile, it is critical that the person be capable of demonstrating basic cognitive and motor skills that will assure the safe operation of the vehicle. Lack of sleep, boredom or consumption of drugs or alcohol can impair a vehicle operator's ability to safely operate the vehicle. Therefore, it is important when designing an impaired driver detection system to continuously evaluate an operator's ability to control the vehicle. Impaired driver detection systems are useful because they avoid or reduce personal injury and property damage by preventing accidents.
An example of a known apparatus for eye finding and tracking which is employed in a vehicle operator drowsiness detection system employs two images of a driver's face. One of the images is obtained by illuminating the driver's face from a first direction, and the other is obtained by illuminating the driver's face from another direction. The two images are processed to detect three-dimensional positions of the driver's eyes. In another, example of a known eye finding and tracking system, an image of a vehicle driver's head is processed to determine the widest portion of the driver's face. From this determination, calculations are performed based on an analysis of the image and assumed geometric relationships of the eyes to the widest portion of the operator's face to define two rectangular regions which should include the operator's eyes.
Eye finding and tracking devices are also useful for other applications. For instance, these devices can be employed in systems designed to monitor the attentiveness of a machine operator, or a person working at a control console such as an air traffic controller. Another example where eye finding and tracking can be useful is in conjunction with an identification system which employs iris pattern matching techniques.
Although systems employing current eye finding and tracking devices work reasonably well for their intended purpose, it is a primary object of the present invention to provide an improved eye finding and tracking system which can determine the location of a subject's eyes within an image of his or her face and thereafter track the changing locations of the subject's eyes in subsequent images with greater accuracy than has been achieved in the past.